Make sure that selection is cleared after tapping.

Source/core/page/EventHandler.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 2245 matching lines @@
     m_clickNode = currentHitTest.innerNode();
     if (m_clickNode && m_clickNode->isTextNode())
         m_clickNode = NodeRenderingTraversal::parent(m_clickNode.get());
 
     PlatformMouseEvent fakeMouseDown(gestureEvent.position(), gestureEvent.globalPosition(),
         LeftButton, PlatformEvent::MousePressed, gestureEvent.tapCount(),
         modifiers, PlatformMouseEvent::FromTouch,  gestureEvent.timestamp());
     bool swallowMouseDownEvent = !dispatchMouseEvent(EventTypeNames::mousedown, currentHitTest.innerNode(), gestureEvent.tapCount(), fakeMouseDown, true);
     if (!swallowMouseDownEvent)
         swallowMouseDownEvent = handleMouseFocus(MouseEventWithHitTestResults(fakeMouseDown, currentHitTest));
-    if (!swallowMouseDownEvent)
+    if (!swallowMouseDownEvent) {
         swallowMouseDownEvent = handleMousePressEvent(MouseEventWithHitTestResults(fakeMouseDown, currentHitTest));
+        // m_selectionInitiationState is initialized after dispatching mousedown event.
+        m_selectionInitiationState = HaveNotStartedSelection;
+    }
 
     // FIXME: Use a hit-test cache to avoid unnecessary hit tests. http://crbug.com/398920
     if (currentHitTest.innerNode())
         currentHitTest = hitTestResultInFrame(m_frame, adjustedPoint, hitType);
     PlatformMouseEvent fakeMouseUp(gestureEvent.position(), gestureEvent.globalPosition(),
         LeftButton, PlatformEvent::MouseReleased, gestureEvent.tapCount(),
         modifiers, PlatformMouseEvent::FromTouch,  gestureEvent.timestamp());
     bool swallowMouseUpEvent = !dispatchMouseEvent(EventTypeNames::mouseup, currentHitTest.innerNode(), gestureEvent.tapCount(), fakeMouseUp, false);
 
     bool swallowClickEvent = false;
@@ skipping 1588 matching lines @@
 unsigned EventHandler::accessKeyModifiers()
 {
 #if OS(MACOSX)
     return PlatformEvent::CtrlKey | PlatformEvent::AltKey;
 #else
     return PlatformEvent::AltKey;
 #endif
 }
 
 } // namespace blink